Hydronic-baseboard-heater-size-calculator, a hydronic baseboard heater is a special type of heater which makes use of liquid such as water to control the temperature within a room.the heater itself is fitted at the bottom of a wall and they are designed to work by sucking in the cold air at the bottom, heating it up and then pushing it back out of the top of the heater.. Alibaba.com offers 120 hydronic baseboard products. about 3% of these are flooring accessories, 1% are mouldings. a wide variety of hydronic baseboard options are available to you,, alibaba offers 376 air calculator suppliers, and air calculator manufacturers, distributors, factories, companies. there are 221 oem, 199 odm, 78 self patent. find high quality air calculator suppliers on alibaba..